Tool controlling mechanisms for excavator with telescopic arm

An excavator comprising:

• a movable body;
• a boom pivotally mounted at a rear end thereof on a front portion of the movable body;
• first hydraulic cylinder means mounted at a rear end thereof on the first portion of the movable body, the first hydraulic cylinder means being provided with cylinder rod means connected at a front end thereof with substantially the central portion of the boom for swinging the boom vertically in a longitudinal direction thereof;
• an outer arm pivotally swingably mounted on a front end of the boom, said outer arm having a rear end and a front end which extends forwardly from the boom;
• a second hydraulic cylinder mounted on a rear surface of the boom, the second hydraulic cylinder being provided with a piston rod connected to a rear portion of the outer arm for changing the angular relationship between the boom and the outer arm;
• an inner arm inserted into the outer arm and movable telescopically relative to the outer arm in the longitudinal direction of the outer arm, said inner arm having a rear end located inside the outer arm and a front end extending forwardly from the outer arm;
• a bucket pivotally connected to the front end of the inner arm;
• a bucket cylinder provided with a piston rod and having a front end operatively connected to the bucket;
• guide means fixed to the outer arm;
• a guide mechanism slidably mounted on the guide means, said guide mechanism having a front end and a rear end, said guide mechanism being connected to a rear end of the bucket cylinder for sliding the bucket cylinder to thereby move the bucket cylinder and its piston rod as a unit in synchronism with the movement of the inner arm so that the angular relationship between the bucket and the inner arm is kept unchanged;
• a third hydraulic cylinder connected to the rear end of the outer arm and having a rod connected to a central portion of the inner arm for moving the inner arm telescopically relative to the outer arm;
• synchronous means for moving the bucket cylinder relative to the outer arm for a distance corresponding to the distance the inner arm moves relative to the outer arm, said synchronous means comprising first sprocket wheel means supported at the rear end of the outer arm, and chain means connected at one end thereof to said guide mechanism and connected at the other end thereof to the rear end of the inner arm, said chain means extending from said guide mechanism into engagement with said first sprocket wheel means so as to be inverted thereby, from said first sprocket wheel means through a space between the inner arm and the outer arm into engagement with said second sprocket wheel means so as to be further inverted thereby and then from said second sprocket wheel means to the rear end of the inner arm;
• and
• interlocking means connected between the guide mechanism and the front portion of the inner arm to maintain a constant spacing therebetween.